Power feed with liquid check



N. ACKERMAN POWER FEED WITH LIQUID CHECK April 11, 1967 2 Sheets-Sheet l Filed June 16, 1964 INVENTOR NATHAN ACKEKMAN Ll au? ATTORN S iin April 11, 1967 N. ACKERMAN POWER FEED WITH LIQUID CHECK 2 Sheets-Sheet 2 Filed June 16, 1964 United States Patent O 3,313,214 PWER FEED WTH L'IQUD CHECK Nathan Ackerman, Lake Success, N.`Y. Sanders, Inc., 678 Berriman St., Brooklyn, NSY. 11208) Filed June 16, 1964, Ser. No. 375,436 14 Claims. (Cl. 92-8) This invention relates to a power feed with a liquid check.

Customarily feed-check mechanisms such as those to which the present invention pertains utilize compressed air as a source of motive power and a liquid, usually oil, as the restraining medium and hence have come to be known as hydropneumatic feeds. The specic embodiment of the invention hereinafter described shows such an a-rrangement. However it should be pointed out that my invention embraces any type of power drive as, for example, a liquid drive, an electric motor drive and a solenoid drive and also embraces liquid checks other than oil as, for example, water, liquid silicones and organic liquids.

Power feeds with liquid checks have become increasingly sophisticated over the years until now they have reached the point where they are a major item of cost, particularly in material removing machinery such as lathes, drill presses, milling machines, planets, grinders, etc.

lt is a principal object of my present invention to provide a power feed with a liquid check which retains the important functions of such feed-check mechanisms but does so with a highly simplified construction, which is relatively inexpensive to produce, which occupies a relatively small space and which is sensitive, accurate, reliable and positive in action.

It is another object of my invention to provide a feedcheck mechanism of the character described having a relatively short axial length, i.e. length in the direction of its stroke.

It is another object of my invention to provide a feedcheck mechanism of the character described wherein a simplified construction is employed to vary the checking rate from fast to slow, i.e. from a fast approach of a tool to a point of contact with material to a slow feed of the tool during removal of material.

lt is another object of my invention to provide a feedcheck mechanism of the character described in which the liquid is fed with substantially no ow restriction into an expansible reservoir during the fast approach phase and through a flow restriction passageway into another and associated expansible reservoir during the slow feed phase whereby to obtain a substantial simplification of structure and of hydraulic circuitry.

It is another object of my invention to provide a feedcheck mechanism of the character described in which the checking liquid is fed from a space of small cross-section to an expanda-ble space of large cross-section in order to minimize displacement of the checking members and thereby to minimize the size and particularly the axial length of the feed-check mechanism.

It is another object of my invention to provide a feedcheck mechanism of the character described which is particularly easy to maintain, set up, adjust and repair.

lt is another object of my invention to provide a feedcheck mechanism of the character described in which a simple yet effective construction is employed to preserve the integrity of the power cylinder.

Other objects -of my invention will in part be obvious and in part will be pointed out hereinafter.

My invention accordingly consists in the features of construction, combinations of elements and arrangements of parts which will be exemplified in then feed-check mechanism hereinafter described and of which the scope ice of application will be indicated in the appended claims.

In the accompanying drawings in which is shown one of the various possible embodiments of my invention,

FIG. 1 is a side view of a power feed liquid check mechanism constructed in accordance with my invention;

FIGS. 2 and 3 are enlarged left hand and right hand fragmentary axial views through said mechanism taken respectively along the lines 2-2 and 3 3 of FIG. l;

FIG. 4 is an enlarged longitudinal sectional view of the annular check valve at the periphery of the settable reservoir plunger;

FIG. 5 is an enlarged detailed view of the adjustable flow restriction valve; and

FIGS. 6 and 7 are enlarged detail views of the fourway valve used to regulate flow of compressed air to the power cylinder, FIG. 6 showing the position of parts of the valve for flow of compressed air to the right hand end of the power cylinder and FIG. 7 showing the position of the parts for compressed air to the left hand end of the power cylinder, in each instance the opposite end of the power cylinder being connected to the atmosphere.

Referring now in detail to the drawings, the reference numeral 10 denotes a power feed liquid check mechanism in the form of a hydropneumatic feed device wherein power is supplied by a fluid under pressure, here shown specifically as constituting compressed air, and in which checking is performed by a liquid, in particular, oil.

Said mechanism as viewed externally (see FIG. i) comprises a large cylindrical casing 12 having a feed end 14. A threaded mounting tip 16 protruding from the feed end is adapted to be coupled to a stationary member of a machine, and a threaded feed rod 18 projecting from the threaded tip 16 is adapted to be coupled to a part of the machine that is to be moved `relative to the stationary member. Thus when the threaded feed rod moves forwardly out of the mounting tip it will move the machine part to be actuated thereby.

At the rear end 20 of the cas-ing are disposed control members 22, 24 for the power actuated liquid check mechanism. These members constitute, for example, tappet valves so connected in a manner to be described that when one valve is manipulated the threaded feed rod will advance forwardly, ri.e. to the left as shown in FIG. l and when the other valve is manipulated the feed rod will move back to retracted position within the casing 12. A rapid approach-slow feed control rod 26 extends outwardly from the rear end of the casing carrying on it a rapid approach adjustment nut 2S which enables the mechan-ism to 'be set so as to subdivide its advance stroke into any deeired proportion of rapid approach to slow feed.

Fora detailed description of the mechanism 10 attention is directed to FIGS. 2 and 3 with occasional reference to FIGS. 4 through 7.

The casing 12 constitutes a sheathing outer air cylinder 30 that is open and internally tapped at the right hand rear end 20 and has an integral wall 32 at the feed end 14. Said wall includes a central aperture 34 from which extends the threaded mounting tip 16 bearing a lock nut 36. The right hand open rear end of the sheathing air cylinder is plugged by a rear end wall 38 of an inner liner air cylinder 4t) which functions as the operative power cylinder. A sealing ring Ll2 is caught between the rim of the sheathing cylinder 3l) and a stub ange on the end wall 33 of the iiner so that a hermetically sealed power cylinder is provided for compressed air.

It will be observed that there is a narrow annular space 39 between the inner surface of the sheathing cylinder and the outer surface of the liner. function, one being to provide a passageway -between the opposite ends of the power cylinder, and the other to provide a protective sheath for the liner. lt will be ob- This space has a duall served that due to the provision of this space if the sheathing cylinder should be struck accidentally with suflicient force to indent it, said space provides room to accommodate the deformation of the sheathing cylinder without creating a `corresponding deformation of the liner which is the part on which the power piston rides.

The rear end wall 38 is centrally apertured to receive the forward end of a cylindrical valve body 44 which provides the casing for a four-way valve that controls the feed of compresed air and the atmospheric connections to the opposite ends of the power cylinder. Any kind of well known four-way valve can be used for this purpose; however I have shown a particularly compact long wearing short stroke positive operating four-way valve which is the subject of my copending application Ser. No.

358,032, tiled Apr. 7, 1964, for Fluid Flow Control Device and Mechanisms Embodying the Same, to which reference is made for a detailed description of its construction. For the sake of convenience I have included at this point a brief description of the construction and operation of said valve.

The valve `body 44 includes a central valve bore 46 (see FIGS. 3, 6 and 7) having an enlarged rear section 48, a valve spindle S is shiftable within said bore, the opposite ends and central portion thereof having a sliding sealing t with the bore through the medium of O-rings 52, 54, 56 respectively. A flange 58 near the rear of the valve spindle forms a control piston that slides in the enlarged rear section 48 being sealingly and slidingly engaged thereto by an O-ring 60. Compressed air is supplied through restricted passageways (not shown) to opposite sides tof the flange, being sealed therein by the O-rings 54, 56. Bleed connections (not shown) are provided to the atmosphere from opposite sides of the ange 58 through the tappet valves 22, 24, respectively. When one of the tappet valves is depressed the corresponding side of the flange 58 has the air pressure therein momentarily lowered and since the opposite side of the ilange is exposed to high pressure air the valve spindle 50 will be shifted toward the -side of low pressure. Specifically when the Ihead of the tappet valve 22 is depressed, the valve spindle 50 will shift to the right and when the head of the tappet valve 24 is depressed, the valve spindle will shift to the left. The right position of the valve spindle is shown in FIG. 7 and the left position in FIG. 6.

The valve spindle 50 has an annular surface passageway 62 in which a control O-ring 64 is seated. Said O-ring protrudes from the valve passageway 62 into an annular opposed internal passageway 66 formed on the surface of the bore 46 of the valve body 44. An annular flow clearance 68 extends from the O-ring 52 to the O-ring 54 between the valve spindle 50 and the valve body 44. This clearance is radially bridged by the control O-ring 64.

Compressed air is supplied, as -indicated by the arrow A, to the body passageway 66. k

In the right position of the valve spindle (FIG. 7) the control O-ring is squeezed between the right hand corner of the body passageway 66 and the left hand corner of the spindle passageway 62. This provides a compressed air connection at the left side of the control O-ring from the body passageway to the How clearance 68 at the left of the control O-ring. A port 70 in the valve body to the left of the passageway 66 is connected by a passageway 72 to the annular space 39, thus leading compressed air to the left hand end of the power cylinder.

The right hand end of the power cylinder is connected by a passageway 74 to a port 76 in the valve body at the right of t-he passageway 66. This provides an atmosphereic connection from the internal bore 78 of the valve spindle through a passageway 80 to the annular spindle passageway 62 past the right hand side of the squeezed control O-ring to the port 76 and thence to the right hand end of the power cylinder. The arrow C denotes such 4 flow through the port 76 and the arrow D the liow to the atmosphere.

In the left position of the valve spindle the connections .are reversed. The control O-ring (FIG. 6) is squeezed between the left hand corner of the body passageway 66 and the right hand corner of the spindle passageway 62. Compressed air ows through the passageway 66 in the direction indicated by the arrow A pa-st the right side of the control O-ning into the How clearance 68 and then out through the port 76 as indicated by the arrow E and passageway '/'4 to the right end of the power cylinder. The left hand side of the power cylinder is connected to atmosphere by flow through the annular space 39, the passageway 72, the port 70 as indicated by the arrow F, the ow clearance 68, past the left side of the control O-ring, and the passageway 80.

In both positions of the four-way valve the control O- ring separates the high pressure air from the atmospheric air.

A power piston 82 is reciprocable in the liner 40, its periphery being grooved to hold an O-ring 84 that ensures a sliding sealing tit between the piston and liner. Said piston is fast on a hollow power piston rod 86 the forward end of which is capped by the threaded feed rod 18. An O-ring 88 forms a sliding sealing fit between the opening 34 in the mounting tip and the external surface of the piston rod.

The power piston will be driven to the right when the :tappet valve 24 is depressed and to the left when the tappet valve 22 is depressed.

The power piston 82 includes a portion that acts as a checking piston. Specically the power piston has a central bore 90 registered with the interior of the power piston rod 86. Said bore is grooved to receive an O-ring 92 that forms a sliding and sealing fit with a stationary rod 94 concentrically disposed within the power cylinder and fast at its right hand end to the valve body 44 and, hence, to the rear end wall 38. Thus the power piston is `guided in'its reciprocal movement by its sliding fit on both the tip 16 and the rod 94. An annular clearance 96 between the piston rod 86 and the stationary rod 94 constitutes a checking cylinder space which is lled with oil so that as the power piston moves from right to left it will sweep oil out of the checking cylinder space.

The oil leaving the checking cylinder 96 ows freely into a first oil reservoir 97 the rear end of which comprises a bore 98 extending rearwardly from the open front end of the stationary axial rod 94. This rst oil reservoir is of an expansible nature, that is to say, it has a moving wall that enlarges the capacity of the reservoir. Said wall is located at the front end of the first oil reservoir and is formed by a plunger 100 which slides within the bore of the moving power piston rod 86. Because the cross sectional area of the first oil reservoir is considerably larger than the cross-sectional area of the oil cylinder 96 the forward axial movement of the plunger 100 relative to the stationary rod 94 within the moving power piston rod to accommodate inow of oil into said iirst reservoir will be only a fraction, for example, one-fth of the axial movement of the power piston 82.

The plunger 100 which forms the shifta'ble wall of the rst oil reservoir 97 constitutes a piston 102 mounted on the forward end of a stem 104. The stem 104 in turn is fastened, as by screwing, on to the forward end of a spindle 106. Hence the stem and spindle will axially translate with the piston 102 with which they are operationally integral.

The rim of the piston 102 is so formed as to provide a sliding and sealing tit with the bore of the power piston rod 86 when the oil pressure on the right hand side of said piston is higher than the oil pressure on the left hand side and the power piston rod 86 is moving forwardly, and to permit ow of oil past the periphery when the oil pressure at the left'hand side of said piston is higher Vthan the oil pressure on the right hand side of the piston, and the power piston rod S6 is moving rearwardly. Thus the sliding and sealing means at such periphery performs the dual function of supplying a sliding and sealing lit and of acting as a check valve.

For this purpose the piston 102 is provided with an annular unit 103 constituting a washer 110, an O-ring 112 and a metal ring 116 forming a unitary assembly. The metal ring 116 is of L-shaped cross-section and is a loose lit on the stem 104. It can experience axial movement thereon to the extent permitted by a retainer C-ring 114 and the back face of the piston 102.

The washer 110 is fast on the metal ring 116 and is of L-shaped cross-section, being formed of a synthetic plas- `tic material having a low coeiiicient of friction, eg., Teflon which is a iiuorocarbon polymer or, more specifically, a tetraiiuoroethylene or a fluorinated ethylene propylene. The circumferential leg of the washer 110 is lightly pressed outwardly by the O-ring 112.

When the oil pressure to the right of the unit 108 is higher than that to the left and the piston rod 86 is moving forwardly, the unit 10S presses against the back face of the piston 102, thereby sealing the piston 102 to the inside of the piston rod 86 which under these circumstances acts as a cylinder, thereby preventing the iiow of oil from the left to the right of said piston. When the oil pressure to the left of the unit 108 is higher than that to the right and the rod 86 is moving rearwardly, the unit 108 shifts away from the back surface of the piston 102 to provide sucient clearance to allow ow of oil from the front face of the piston 102 to the reservoir 97 at the back face of said piston.

For convenience, the tip of the spindle 106 is screwed into a female threaded bore at the rear end of the stern 104. The stationary axial rod 94 within which the spindle 106 axially reciprocates includes a bore 118 that is a reduced diameter continuation of the `bore 98 and that extends to the extreme right hand end of said rod 94 where it is exposed to the atmosphere through the spindle bore 78 so that the interior of the rod 94 is at atmospheric pressure up to the base of the large diameter bore 98. The zone between the bores 98, 118 is sealed, as by a bushing 120 and an O-ring 122. Said bushing is screwed into a tapped section at the forward end of the bore 11S and provides an inwardly facing annular groove in which the O-ring 122 is located. The O-ring forms a sliding and sealing tit with the external surface of the spindle 106 so that as said spindle reciprocates there will be no leakage of oil from the iirst oil reservoir 97 to the atmosphere.

Means is included to bias the spindle 106 and, therefore, the plunger 100 to the idle, i.e. retracted, position shown in FIGS. 2 and 3 wherein the plunger is located adjacent the forward end of the stationary axial rod 94. Said means constitutes a helical compression spring 124 that encircies the moving spindle 106 and is located in the clearance between said spindle and the stationary rod 94. The forward end of the spring is seated against a stationary ring 126 caught between the bushing 120 and a shoulder in the tapped section into which the bushing is screwed. The rear end of the spring is seated against a movable ring 128 that is located on the spindle 106 between the ends thereof. The rear end of said spindle is threaded as at 130, the ring 128 being screwed up to the forward end of such threaded portion.

When the plunger 100 moves forwardly under the thrust `of the oil flowing into the first reservoir 97 as oil is swept out of the oil lcylinder 96 by the checking oil piston (the O-ring) 92 the spindle 106 will move forwardly and compress the spring 124 between the rings 126, 128. The opposition thus offered to forward movement of the plunger is of a relatively low order, e.g. in the order of a few pounds so that there is no marked restraint to forward movement of the plunger and hence no marked restraint to forward movement of the power piston 82 whereby the feed rod 18 will move through the approach phase of its stroke quite rapidly, bein-g held back only by the 4low opposition to ow offered by the checking cylinder.

The end of the rapid approach phase of the stroke is abruptly halted by abutment of the fast-slow adjustment disc 2S against the rear surface of the valve body 44. Said fast-slow adjustment disc includes an adjustment nut 132 screwed on the threaded portion 130 of the spindle 106, this threaded portion forming the fast-slow control rod 26. The disc 28 further includes a washer 134 in back of the adjustment nut 132 and a lock nut 136 in back of the washer. When it is desired to change the position of the disc 28 the lock nut is backed off, the adjustment nut is turned to its new axial position and the `lock nut then tightened against the washer to retain the adjustment nut in such new position.

When the disc 28 strikes the valve body so as to check further forward movement of the plunger the power piston S2 no longer is able to quickly move forward in the rapid approach phase of its stroke because the oil in the cylinder 96 no longer can freely flow into the first oil reservoir 97 inasmuch as its expandable wall constituting the plunger 100 has now been rendered stationary. However I provide an alternate flow passageway for the oil leaving the checking cylinder 96 `which alternate flow passageway leads through a restricted flow zone into a second expansible reservoir which for the sake of compactness, economy and ease of repair is located adjacent to the first reservoir and coaxial therewith inside the hollow power piston rod 86. The restricted flow zone by offering a greater impedance to the flow of oil therethrough than that which was offered to the oil flowing from the oil checking cylinder 96 to the first oil reservoir 97 provides a check or restraint upon the forward movement of the power piston 82 and the feed rod 1S so as to reduce the speed of movement of said rod to some desired rate during slow infeed.

The second oil reservoir which has been denoted by the reference numeral 138 has its side wall formed by the forward part of the bore of the moving power piston rod S6, said forward part being that section of the power piston rod in front of the plunger 100, it being observed that said plunger moves within the power piston rod during the forward stroke of the power piston. It will be recalled that the plunger 100 does not have a one-to-one movement with the piston rod 86 inasmuch as the crosssectional area of the lirst oil reservoir 97 is greater than the cross-sectional area of the oil checking cylinder 96. Accordingly the plunger 100 only advances at any given time a fraction of the distance advanced by the piston rod 86.

The rear wall of the second reservoir 138 is formed by the front of the plunger 100 so that, in elect, said plunger separates the first oil reservoir 97 from the second oil reservoir 138. The front wall of the second reservoir is defined by a second plunger 140. The second plunger is spaced forwardly of the first plunger 100 and has a sliding and sealing fit with the bore of the power piston rod effected through the medium of an O-ring 142.

The second plunger is suitably biased toward the rst plunger, as by a tension spring 144 having one end anchored at the base of a blind Well 146 in the second plunger and the other end anchored at the base of a blind well 14S in the first plunger 100. The means for anchoring the tension spring in the Well 146 comprises a plug 150 at the base of the well 146, said plug having an annular groove in which a turn of the spring 144 is caught. The shank of the plug extends through the base of the well 146 where it is hermetically sealed and receives a washer 152 and nut 154 at its tip.

The outer face of the forward end of the second plunger 140 can be viewed through a slot 156 extending transversely through the feed rod 18.

It will be observed that the forward end of the plunger 140 is of reduced diameter and makes a non-sealed sliding 7 fit with a bore 158 provided within the feed rod 18, said bore being closed at its forward end and at its rear end communicating with the air lled hollow front interior portion of the power piston rod 86.

The rear end of the spring 144 is anchored by having a turn thereof received in an annular groove formed in a valve body 160 screwed in to the closed end of the well 148. The spring 144 desirably is lighter than the spring 124 although this is not essential.

It will be appreciated that when the power piston 82 moves forwardly and the oil is expressed from the checking cylinder 96 into the oil filled first reservoir 97 so as to force the plunger 100 forwardly, the second plunger 140 will move forwardly at the same speed as the first plunger because the second oil reservoir space between the two plungers is filled vwith oil. However this speed is less than the speed of the piston rod 86 so that when the feed rod 18 moves forwardly during the rapid approach phase of the advance stroke the bore 158 will leave the plunger 140 behind it.

As noted previously there is an oil filled flow passageway between the oil filled first reservoir 97 and the oil filled second reservoir 138 which fiow passageway includes a restricted fiow zone. Specifically I provide a broad annular groove 162 which constitutes the entrance at the first reservoir to said flow passageway between the two reservoirs. This groove is located on the external surface of the stem 104 of the first plunger 100, said stem being disposed in the first oil reservoir which latter constitutes the bore 98 at the forward end of the stationary rod 94 as well as the space forwardly of this bore and in back of the first plunger 100.

It is highly desirable to include a filtering means in the flow passageway between the two reservoirs in order to prevent the intrusion of solid particles into the restricted flow zone where the particles could partially clog said zone and thus uncontrolla'bly affect the rate of restricted flow. Accordingly a lter element 164 is seated in the groove 162. The filter element comprises a few, e.g. several, layers of a fine, e.g. 125 mesh, screen.

The liow passageway further includes a radially disposed bore 165 leading from the groove 162 to an axial bore 166 in the stem 104. The axial bore 166 runs to a chamber 168 at the bottom of the female threaded bore in the stem 104 into which the spindle 106 is screwed. An offset longitudinal bore 170 extends forwardly in the stem 104 from the chamber 168 to the well 148 in the first plunger 100 and hence connects this chamber to the second reservoir 138. Thereby oil can fiow from the first oil reservoir 97 through a iiow passageway constituting the groove 162, the radial bore 165, the axial bore 166, the chamber 168 and the offset bore 170 to the sec nd oil reservoir 138.

The aforesaid iiow pasageway includes a restricted flow zone, preferably a restricted flow zone which is adjustable whereby to vary the checking (restraining) effect of liquid fiowing through the fiow passageway between the two reservoirs. A suitable method of providing a restricted flow zone constitutes the insertion of a pin 172 (see also FIG. in the axial lbore 166. The pin is of a diameter slightly less than that of the axial bore, for example leaving two-thousandths of an inch diametral clearance.

Suitable means hereinafter to be described is provided to hold the pin 172 within the axial bore 166 and to adjust the axial position of the pin therein. The degree of flow restriction is a function of the extent 4to which the pin 172 projects into the axial bore 166 from the chamber 168.

As the power piston 82 moves forwardly within the liner 40 oil first will be swept from the oil checking cylinder 96 by the oil piston 92 into the first reservoir 97 while the plunger 100 moves forwardly to accommodate it until the adjustment disc 28 strikes the valve body 44 to render the first plunger immobile. Thereafter oil swept out of the cylinder 96 will ow into the second reservoir 138 past the pin 172 while the second plunger 140 moves forwardly to accommodate the ingress of oil. The concurrent speedier forward movement of the power piston rod 86 does not affect forward movement of said two plungers except to reduce frictional drag at the seals 110, 142. The rate of forward movement of the second plunger will be less than that of the first plunger 100 inasmuch as the cross-sectional area of the second reservoir is larger than the cross-Sectional area of the first reservoir, the latter being partly filled with the spindle 106.

To review the operation of the mechanism 10, when compressed air is introduced to the right hand side of the power piston 82 upon actuating the tappet valve 22 said piston will advance to the left. During the first phase of the advance stroke the movement will be rapid because the oil expressed from the cylinder 96 by the O-ring 92 flows into the first reservoir 97 in back of the plunger 100 without any appreciable `flow restriction. The plunger 100 will slowly move forwardly to accommodate this influx of oil into the first reservoir and the disc 28 will advance forwardly with it. Eventually the disc will strike the valve body 44.

With the plunger 100 stationary no further oil can be accommodated in the first reservoir and the oil which continues to be swept out of the oil cylinder 96 now Iiows from the first reservoir into the second reservoir through the high resistance path including the restriction zone formed by the axial bore 166 and the pin 172. The increased resistance slows down the rate of advance of the power piston and builds up a high oil pressure in the first reservoir. This constitutes the slow feed phase of the advance stroke. A.

At some point during the slow feed phase the forward movement of the power piston 82 will be halted as by the moving part of the machine striking a stop. Thereupon the tappet valve 24 is actuated to reverse the application of compressed air to the power piston and drive it back to the right hand side of the air cylinder. As the power piston starts its retrograde movement oil will fiow back into the oil cylinder 96 the initial iiow being from the first reservoir 97 in back of the plunger 100 and being engendered by the pressure of the spring 124.

Since the pressure exerted by the spring 124 on the oil in the rst reservoir exceeds the pressure exerted by the spring 144 on the oil in the second reservoir the peripheral check valve yon the plunger 102 remains closed during the initial part of the retrograde stroke. Hence the second reservoir remains substantially full until the plunger 102 reaches the forward end of the rod 94. This is advantageous for a type of material removing operation known as pecking in which a tool is advanced to work and then repeatedly backed off slightly and smartly brought back against the work. Since the plunger 102 is the first to retract upon a retrograde stroke, if the direction of movement of the returning power piston is changed while it is still near the end of its full stroke the power piston will advance rapidly inasmuch as oil then can fiow into the now partially contracted first reservoir 97.

Means is included to vary the axial position of the pin 172 within the axial bore 166 of the stern 104. Said means constitutes an elongated metering screw 174 which is nested within the axial Ibore of the spindle 106. The metering screw is substantially coextensive with the spindle and is itself provided with an axial bore 176. At the forward end of the metering screw the axial bore is enlarged to -receive the rear end of the pin 172. A shoulder 17 8 at the juncture between the two different diameters of the bore 176 provides a seat against which the rear end of the pin 172 abuts.

At the rear end of the spindle 106 I fixedly mount an internally tapped sleeve 180 that mes-hes with a threaded portion 182 on the external surface of the rear end of the metering screw. Thereby when the metering screw is turned the shoulder 178 will either advance or retract within the spindle 106 depending upon the sense in which the screw is turned and it will either advance the pin 172 further into the axial bore 166 to increase flow restriction or it will permit the pin to shift further out of said bore under the pressure of oil fiowing through said axial bore into the chamber 163.

To facilitate rotation of the metering screw a knurled collar 184 is fastened on to its rear end.

The threaded portion 182 terminates at a forward shoulder 186 to prevent the metering screw from accidentally being backed too far out of the spindle 1116.

Inasmuch as oil under pressure is present in the chamer 168 to which the exterial surface of the metering screw 174 is exposed, O-rings 186 seal the space between the exterior of the metering screw and the bore of the spindle 106 to prevent leakage of such oil to the atmosphere at the sleeve 180.

Despite the presence of the sundry seals, some oil inevitably seeps out of the checking system and should be replaced. For this purpose I provide an oil replenishing means which includes the axial bore 176 since it has a convenient access to the oil system through the chamber 168. The rear end of the bore 176 is normally closed by a check valve constituting a ball 190 biased by a spring '192 against the forward end of a passageway 194 concentric with the bore 176 and located in the collar 184. The passageway 194 leads to a tapped socket 196 that during regular use is stoppered by a plug 198.

To replenish the oil the plug 198 is unscrewed and replaced by an oil fitting, and oil under pressure is forced into the socket. Such oil will open the check valve constituting the ball 190 and will supply additional oil to the checking system through the bore 176 and past the pin 172 into the chamber 168. Inasmuch as said chamber is directly connected to the second reservoir 138 the oil will not tend to lift the piston 100 oftr the forward end of the stationary rod 94 but rather will shift the piston 140 forwardly. Introduction of replenishing oil should be effected when the power piston is at the right hand end of the power cylinder. At this time the two reservoirs are in their most contracted states. Therefore introduction of the fresh oil will shift the piston 140 forwardly. An appropriate mark is placed on the outside of the feed rod 18 adjacent the slot 156. Sufiicient oil is introduced into the checking system to Abring the outer face of the forward end of the piston 140 level with such mark. It will be apparent that the mark cannot be used to regulate introduction of oil into the checking system at any other position of the power piston since the forward end of the piston 140 would be backed partly or entirely out of the :bore 158.

1t has been assumed in the foregoing description of the operation of the mechanism that the bottom of the well 148 is closed so that there is no connection from the second reservoir 138 to the first reservoir 97 except through the flow restriction Zone. However it is within the scope of my invention to provide such connection, i.e. a connection shunting the iiow restriction zone. The shunting connection is'in the form of a passageway 290 which extends from the radial bore 165 to an axial bore 2411 in the valve body 169. Said bore 201 contains a ball 292 which is biased by a spring away from seat in the `valve body. As long as the pressure in the first reservoir exceeds that in the second reservoir the ball will be held against its seat but when the pressures in the two reservoirs are the same the spring will unseat the ball.

The said ball 202, together with the passageway 200 and the bore 261, acts as a pressure sensing means. Thus when the feed rod 18 is suddenly halted as by a member on the feed mechanism of the material removing machine striking a stop, the ow of oil through the restricted zone will suddenly cease so that the high pressure which prevailed in the first reservoir 97 due to liow of oil through the restricted zone drops and the oil pressures in the two reservoirs will be approximately equal. Thereupon the ball 202 will become unseated to open the shunt passageway between the two reservoirs. At this time while the power piston 82 still presses forwardly the heavy spring 124 will force oil to flow through the shunt passageway 20G from the first reservoir into the second reservoir thereby allowing the plunger 108 to initiate a retrograde movement. As a result the adjustment disc 28 will start to back off from the valve body 44. A suitable electrical sensing means such as a uni-directional responsive feeler 203 of a momentary switch (not shown) is disposed in the retrograde path of travel of the disc 28 and the same when actuated may perform any desired function as, for example, cause actuation of the tappet 24 to relverse the direction of the power piston 82.

It thus will be seen that 1 have provided a mechanism which achieves the several objects of my invention and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes ymight be made in the embodiment set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and useful and desire to be secured by Letters Patent,

1. In combination a power driven member and a restraining means therefor, said restraining means including a cylinder, a piston movable as a function of the movement of the power driven member, a hollow piston rod carried by the piston, a liquid in said cylinder compressed by movement of the piston in at least one direction, a first reservoir within the piston rod including a first movable wall within the piston rod, a first passageway connecting the cylinder with the first reservoir, a second reservoir Within the piston rod including a second movable wall within the piston rod on the said one direction side of the first movable wall, a second passageway connecting the first reservoir with the second reservoir, a restricted fiow zone in the second passageway, and limit means including a member carried by the first wall and externally abutting the cylinder to stop at a predetermined point the movement of the first Wall in a direction expanding the -volume of the first reservoir so that the power driven member may move rapidly while the oil expressed from the cylinder fiows into the first reservoir and the first wall thereof moves in a direction expanding the volume of the first reservoir until such movement of the first wall is stopped and thereafter the movement of the power driven member is restrained by the impedance to fiow of liquid expressed from the cylinder and owing into the second reservoir through the restricted flow zone.

2. A combination as set forth in claim 1 wherein the first movable wall of the first reservoir is a wall of the second reservoir.

3. A combination as set forth in claim 1 wherein a shunt connection is provided within the piston rod and across the restricted flow zone and in which valve means located in the shunt connection is held closed by a greater pressure in the first reservoir than in the second reservoir, said valve means opening when the pressure in the second reservoir is at least about equal to the pressure in the first reservoir.

4. A combination as set forth in claim 1 wherein means is included within the piston rod and which is responsive to a drop in pressure in the first reservoir to at least about the pressure in the second reservoir so as to sense halting of the movement of the power driven member.

5. A feed-check mechanism including a power cylinder, 'a power piston reciprocable in said cylinder responsive to unbalanced pressures on opposite faces thereof, a hollow power piston rod on which the power piston is secured and which is reciprocable with the piston relative to the power cylinder, a stationary rod in the hollow power piston rod, a liquid containing checking cylinder defined by the space between said rods, an oil checking piston movable with the power piston and operable to compress liquid in the checking cylinder upon movement in one direction, a first reservoir within the hollow power piston rod, said first reservoir including a first movable wall within the hollow power piston rod, a first passageway connecting the checking cylinder with the first reservoir, a second reservoir within the hollow power piston rod, said second reservoir including a second movable wall within the hollow power piston rod on the said one direction side of the first wall, a second passageway connecting the first reservoir with the second reservoir, a restricted flow zone in the second passageway and limit means including a member carried Irby the first wall and externally abutting the cylinder to stop at a predetermined point the movement ofthe first wall in a direction expanding the volume of the first reservoir.

6. A feed-check mechanism as set forth in claim wherein the oil checking piston constitutes a bore in the power piston and means disposed in said bore and making a sliding and sealing fit with the stationary rod.

7. A feed-check mechanism as set forth in claim 5 wherein the power cylinder and the stationary rod are coaxial and coextensive.

8. A feed-check mechanism as set forth in claim 5 wherein the first movable wall is a first plunger forming a sliding and sealing fit with the interior of the hollow power piston rod, wherein the first reservoir is the space in the hollow power piston rod between the first plunger and the stationary rod, wherein the second movable wall is a second plunger forming a sliding and sealing t with the interior of the hollow power piston rod, and wherein the second reservoir is the space in the hollow power piston rod `between the two plungers.

Y 9. A feed-check mechanism as set forth in claim S wherein the restricted fiow zone has an adjustable settable impedance -to liquid flow.

10. A feed-check mechanism including a power cylinder, a power piston reciprocable in said cylinder responsive to unbalanced pressures on opposite faces thereof, a hollow power piston rod on which the power piston is secured and which is reciprocable with the piston relative to the power cylinder, a stationary rod in the hollow power piston rod, a liquid containing checking cylinder defined by the space between said rods, an oil checking piston movable with the power piston and operable to compress liquid in the checking cylinder, a first reservoir within the hollow power piston rod, said first reservoir including a first movable wall within the hollow power piston rod, a first passageway connecting the checking cylinder with the first reservoir, a second reservoir within the hollow power piston rod, said second reservoir including a second movable wall within the hollow piston rod, a second passageway connecting the first reservoir with the second reservoir, a restricted flow zone in the second passageway and limit means to stop at a predetermined point the movement of the first wall in a direction expanding the volume of the first reservoir, the first movable wall constituting a first plunger `forming a sliding and sealing fit with the interior of `the hollow power piston rod, the first reservoir being the space in the hollow power piston rod between the first plunger and the stationary rod, the second movable wall constituting a second plunger forming a sliding and sealing fit with the interior of the hollow power piston rod, the second reservoir being the space in the hollow power piston rod between the two plungers, the stationary rod being hollow, the first plunger including a spindle extending through the hollow stationary rod and the limit means including a member fast to the spindle externally of the power cylinder and adapted to strike another member carried by the cylinder when the first plunger moves to the predetermined point during expansion of the volume of the first reservoir.

11. A feed-check mechanism as set forth in claim 10 wherein the first plunger has a stem between it and the spindle, wherein the second passageway is located in said stem and includes a portion coaxial of the stem and spindle, wherein a pin in said portion constitutes the restricted fiow zone, wherein the spindle is hollow, and wherein a metering screw within the hollow spindle is arranged to vary the position of the pin in said axial portion of the second passageway so as to vary the impedance to liquid flow of the restricted flow zone.

12. A feed-check mechanism as set forth in claim 11 wherein the metering screw is hollow to provide a passageway for supplying replenishing liquid to the second reservoir.

13. A feed-check mechanism including a power cylinder, a power piston reciprocable in said cylinder responsive to unbalanced pressures on opposite faces thereof, a hollow power piston rod on which the power piston is secured and which is reciprocalble with the piston relative to the power cylinder, a stationary rod in the hollow power piston rod, a liquid containing checking cylinder defined by the space between said rods, an oil checking piston movable with the power piston and operable to compress liquid in the checking cylinder, a first reservoir within the hollow power piston rod, said first reservoir including a first movable wall within the hollow power piston rod, a first passageway connecting the checking cylinder with the first reservoir, a second reservoir within the hollow power piston rod, said second reservoir including a second movable wall within the hollow power piston rod, a second passageway connecting the rst reservoir with the second reservoir, a restricted fiow zone in the second passageway, limit means `to stop at a predetermined point the movement of the first wall in a direction expanding the volume of the first reservoir, and a pressure sensing means constituting a spring loaded relief valve connecting the two reservoirs, said valve being oriented and spring loaded to close when the pressure in the first reservoir exceeds the spring loading on the valve plus the pressure in the second reservoir.

14. A feed-check mechanism as set forth in claim 13 wherein each reservoir includes a means biasing its associ-` ated movable wall in a direction reducing the volume thereof and wherein the biasing means affiliated with the first reservoir is stronger than the biasing means affiliated with the second reservoir.

References Cited by the Examiner UNITED STATES PATENTS 1,448,624 3/ 1923 Gordon 92-240 1,592,266 7/1926 Hamer 92--171 1,670,299 5/ 1928 Bonner et al. 92-171 1,998,873 4/1935 Kinsbury 92-9 2,624,318 1/ 1953 Walder 92-9 2,672,129 3/ 1954 Fischer 92-171 X 2,686,402 8/ 1954 Samuel 92-240 2,926,696 3/ 1960 Kolm 92-78 X 2,934,093 4/1960 Bleasdale 92-171 X 3,146,680 9/1964 Hutter et al. 92-12 3,200,716 8/ 1965 LeSage 92-417 X FOREIGN PATENTS 821,319 10/1959 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

SAMUEL LEVINE, MARK M. NEWMAN, Examiners.

I. C. COHEN, Assistant Examiner. 

1. IN COMBINATION A POWER DRIVEN MEMBER AND A RESTRAINING MEANS THEREFOR, SAID RESTRAINING MEANS INCLUDING A CYLINDER, A PISTON MOVABLE AS A FUNCTION OF THE MOVEMENT OF THE POWER DRIVEN MEMBER, A HOLLOW PISTON ROD CARRIED BY THE PISTON, A LIQUID IN SAID CYLINDER COMPRESSED BY MOVEMENT OF THE PISTON IN AT LEAST ONE DIRECTION, A FIRST RESERVOIR WITHIN THE PISTON ROD INCLUDING A FIRST MOVABLE WALL WITHIN THE PISTON ROD, A FIRST PASSAGEWAY CONNECTING THE CYLINDER WITH THE FIRST RESERVOIR, A SECOND RESERVOIR WITHIN THE PISTON ROD INCLUDING A SECOND MOVABLE WALL WITHIN THE PISTON ROD ON THE SAID ONE DIRECTION SIDE OF THE FIRST MOVABLE WALL, A SECOND PASSAGEWAY CONNECTING THE FIRST RESERVOIR WITH THE SECOND RESERVOIR, A RESTRICTED FLOW ZONE IN THE SECOND PASSAGEWAY, AND LIMIT MEANS INCLUDING A MEMBER CARRIED BY THE FIRST WALL AND EXTERNAL- 